The invention relates generally to air intake system for internal combustion engines, and more particularly to an intake system that permits enhanced efficiency capable of meeting stringent demands of reduced emissions standards.
Many off-road vehicles are known for various applications that demand considerable power output and high reliability. Construction and agricultural applications, for example, make use of trucks, tractors, combines, and specialized vehicles of numerous configurations, many utilizing powerful diesel engines as their primary power plant. Historically, these vehicles have emphasized power and reliability first and foremost, with issues such as fuel consumption and emissions being important, but somewhat secondary. Increasingly, however, ever more stringent requirements are being placed on these vehicles to reduce fuel consumption and emissions, while still providing the power output needed for their particular applications.
One standard currently requiring significant redesign in such vehicles is the Tier 4 emission regulations being implemented by the U.S. Environmental Protection Agency. These regulations provide guidance for off-road diesel engines, and affect certain higher horsepower engine ratings. They call for significant reductions in particulate matter (smoke), as well as in oxides of nitrogen. Some adaptations contemplated to address these standards include selective catalytic reduction, in which engine exhausts passes through a catalytic chamber where it is sprayed with a non-toxic mixture of chemical urea and purified water. When the mixture combines with hot exhaust in the catalytic chamber, it is broken down into water vapor and nitrogen. Advantages of such systems include longer service intervals, lower fuel consumption, and wider fuel compatibility.
These and other approaches to still must satisfy considerable air intake demands of the engines, and must provide a high degree of inlet filtration. This is particularly true for vehicles operating in challenging environments, such as construction and farming, in which dirt and dust may be present in relatively high concentrations. Current designs may not be suitable for these more demanding applications, or may operate as unacceptably low levels of efficiency.
There is a need, therefore, for improved air intake systems for off-road vehicles.